1. Field of the Invention
The present invention is related to a blade system for use in a wind turbine in which the wind rotates a rotor shall to a generator that produces electrical energy. The blade system has a blade arm with blade assemblies that have rotatable flaps.
2. Description of Related Art
The amount of kinetic energy that can be harvested for the production of electricity is a function of wind velocity, surface area and efficiency of the blade system. The current propeller-type wind turbines harvest most of the wind energy today. The blades are 35 meters in length and currently newer turbines will use blades of 42 meters in length. There are two fundamental problems with the propeller design.
First, the propeller design has a natural tendency to “fly” in a direct line just as a plane would fly. The ability to harness the blades to the pole is easily maintained in winds below 50 miles per hour. Winds above this, however, could cause the blades to fly off the pole. For this reason the design for wind turbines must be “furled” or “battened down” in these high winds. Yet it is these high winds that process the greatest kinetic energy since the wind velocity cubed (V3) determines the energy harvest. As an example, a wind velocity of 50 miles per hour does not contain twice the energy as a 25 mile per hour wind but rather (503+253) eight times as much.
The second problem with the current propeller design is that such propeller-type units must face into the wind. If the unit fails to rotate into the wind the electrical harvest will drop enormously and possibly to zero. Finally, while not an issue of generation, the propeller designs kill migratory birds. For these reasons the horizontal designs have been considered. In a horizontal design the unit spins on an access horizontal to the earth's surface rather than perpendicularly as propeller designs do.
Horizontal units, however, have their own problems. The first problem is that the horizontal units are top heavy. For this reason they are very small and most suited for homes and office units but not for the primary energy of electrical energy grid. A second problem is inefficiency due to drag. If the blades are flat the same wind hits the left blade as hits the right blade resulting in no movement. In order to reduce drag the blades are in a fixed pitched position; the blade being “pushed” by the wind is in a fixed pitched position so that more surface faces the wind while the trailing blade moving into the wind and not with the wind is in a fixed pitched position so that it leads into the wind on edge.
While this does allow directional movement there is drag and inefficiency which still remains significant. The horizontal design does, however, work without ever having to turn into the wind as does the propeller design.